In a scathing report released Thursday, federal authorities said that a culture exists at Cook County Jail in which inmates are systematically beaten by guards and medical care is so substandard that some inmates have died.

In the 98-page report, the U.S. attorney's office in Chicago and the Justice Department's Civil Rights Division called the complex violent and pointed to a raft of problems ranging from unsanitary conditions to inadequate mental health care and suicide-prevention measures.

At a news conference, U.S. Atty. Patrick Fitzgerald called on the Cook County Board and Sheriff Tom Dart to fix a dangerous jail that is "woefully inadequate."

"Everything we've seen from them suggests they recognize what the problem is," Fitzgerald said. "Now the rubber hits the road."

Dart, who is responsible for the jail, blasted the findings, saying he felt betrayed after his office fully cooperated with the probe, only to have the report ignore their reform efforts.

"The thing that I found so disturbing was that I welcomed them in here," Dart said in an interview at his office at the West Side jail. "I gave them access to everything with the hope that they would be yet another set of eyes, that they'd come up with a couple of suggestions about how I could do things better.

"For them to come out with criticism and then flavor it with some horribly incendiary language and try to paint this picture that we don't care or we don't know is completely inaccurate and horribly unprofessional."

The largest facility of its kind in the country, the jail long has been criticized as understaffed and overcrowded. In 2004 a special Cook County grand jury condemned the handling of a 1999 mass beating of inmates by correctional officers, and inmates regularly complain to criminal court judges about their treatment there.

For more than a quarter-century, the jail has been monitored by a federal judge as a result of the settlement of a lawsuit over overcrowding. But the Justice Department report delivered to Cook County last week made it clear that oversight hasn't been enough.

The report detailed numerous incidents in which guards used excessive force in response to verbal insults, failures by inmates to follow instructions or violence against jail staff. Inmates have been punched, stomped, choked and struck with objects, often by multiple officers, suffering black eyes, broken jaws, loosened teeth, fractured noses and ribs, and head trauma, the report said.

"We believe that, despite management's efforts, a culture still exists at [the jail] in which the excessive and inappropriate use of physical force is too often tolerated," the report said.

In July 2007, a mentally ill inmate who exposed himself to a female corrections officer was taken to a clothing room where a group of guards handcuffed and beat him, leaving him with severe head injuries, the report said. In August 2006, a stabbing of a guard set off a mass beating of inmates in retaliation, an incident under federal investigation.

The report said the jail's intake area for inmates was particularly plagued with problems. In one alleged incident, guards in May 2006 beat an inmate so severely for refusing to obey orders that he needed to be taken to a trauma center and placed on a respirator.

According to the letter, the inmate was wandering around the intake area, asking for methadone, a legal drug that can be prescribed to heroin addicts. A guard told him to return to his holding pen and, when he refused, more than one guard beat him, the report said.

He was hit with a radio, and a guard smashed the inmate's dentures under his boot when they fell out of his mouth, the report said. He suffered multiple broken bones and a collapsed lung, authorities said.

No one wants guards hurt or insulted, Fitzgerald said, "but the response is not to engage in beatings of the inmates, certainly not organized beatings, and not beatings that end up with inmates being hospitalized."

Dart countered by saying incidents involving the use of force are down 22 percent so far this year, with 280 incidents between inmates and guards.

Dart said the federal review ignored reforms he enacted in how his office investigates misconduct at the jail and made no mention that he formed a blue-ribbon panel of prosecutors to revamp the internal affairs process. He hired a high-ranking FBI agent to lead that program.

The sheriff acknowledged that there has been abuse of inmates by correctional officers but said the new Office of Professional Regulations aggressively investigates allegations. When they are substantiated, suspensions and terminations are recommended, he said.

Federal investigators, who visited the jail in summer 2007, found overall security lacking, enabling inmates to easily harm one other because of staffing woes. Two inmates were killed by other inmates in 2006, the report said, and the facility endured 35 fights during just one week in March 2007.

The report also found that medical services at the jail fell below constitutionally required standards of care in more than a dozen areas, including in staffing and emergency care. Some inmates died needlessly as a result, the Justice Department concluded.

In early 2006, a female inmate died of an untreated infection that was a common complication of HIV, investigators found. She went untreated for weeks despite an abnormal X-ray that identified a problem, the report said.

In an August 2006 case, an inmate's leg was amputated because of a bone infection improperly treated at the jail. In late 2006, another inmate died of sepsis after a jail staffer failed to take him to an appointment for post-operative care for a gunshot wound, the report said.

David Fagus, chief operating officer of Cermak Health Services, the jail hospital, pointed out that Cermak's budget was cut to about $31 million in 2007 from $40 million in 2006. Currently, Cermak has 394 employees, about 70 fewer than in 2006, budget documents show.